1. Field of the Invention
The present invention relates to an opening/closing device for a mouth of a container such as a paper container, a can, a bottle or the like, and a process for making the same.
2. Description of the Prior Art
The inventor of this invention invented previously the above-mentioned type of device as shown in FIGS. 19 to 21, and a Utility Model application was filed therefor and laid open at the Japanese Patent Office (Japanese Utility Model Application No. 60-161811(1985)).
The present invention relates to improvements for the above-referred laid-open invention, and so, at first description will be made on the above-referred laid-open invention.
In FIGS. 19 to 21, reference numeral 51 designates a mount portion, numeral 52 designates a pouring mouth, numeral 53 designates a hinge and numeral 54 designates a lid. The entire assembly is formed of synthetic resin. Reference numeral 55 designates a gap space for improving a hinge effect. In addition, a metallic film 56 is made to adhere onto the upper surface of the assembly, that is, onto the upper surface of the lid 54 and the upper surface of the pouring mouth 52. By way of example, this metallic film 56 consists of an aluminium foil with synthetic resin layers (not shown) formed on both of its surfaces. The lid 54 is formed so as to have a slightly larger diameter than the pouring mouth 52.
The above-mentioned device is mounted on a paper container or the like. It is to be noted that in FIGS. 19 and 21, reference numeral 57 designates a nip portion of the metallic film 56. A user of a container 58 nips portion 57 and pulls it in the direction of arrow A57 to open the lid 54, and thereby he can pour out the liquid in the container 58. For instance, this device is provided on a paper container containing milk, and when the device is opened to drink a part of the milk and then the residual is accommodated in a refrigerator or the like, the device can be closed in a simple manner by pushing the lid 54 from the outside into the pouring mouth 52.
However, in such a device, since the lid 54 is formed so as to have a larger diameter then the pouring mouth 52, although only slightly, it is somewhat difficult to push the lid 54 into the pouring mouth 52, and it necessitates some effort. Consequently, in some cases the device is used with the lid 54 not perfectly pushed into the pouring mouth although it is pushed in the desired direction, and in such cases there is a fear that floating dust and dirt in the atmosphere may possibly enter the container through the pouring mouth.
Furthermore, it was discovered that the above-mentioned laid-open device involved problems also with respect to the process for making the same. That is, in the case of thermally bonding the metallic film 56 onto the upper surface of the pouring mouth 52, a support table not shown is applied to the lower surface of the lid 54 and the metallic film 56 is pressed from above while it is being heated by means of a heating plate not shown, but it is impossible to press the upper surfaces of the lid 54 and the pouring mouth 52, respectively, with favourable pressures because the pressing is effected for both the upper surfaces of the lid 54 and the pouring mouth 52 in one action. Consequently, the metallic film 56 would be strongly bonded to the upper surface of the pouring mouth 52, resulting in the problem that upon use the metallic film 56 can be hardly pealed from the pouring mouth 52. This is caused also for the following reasons. That is, in Japan, synthetic resin to be used on the inside of a paper container or the like for containing milk is limited to polyethylene, and in the event that the pouring mouth 52 and the inner surface coating of the metallic film 56 are both made of polyethylene, they would be more strongly bonded because of the same kind of resin.
The present invention has been made for the purpose of resolving this problem, and one object of the present invention is to provide an opening/closing device for the mouth of a container, which can very easily close a pouring mouth upon reuse of the device after initial opening thereof, by improving the above-referred laid-open opening/closing device. In addition, another object of the invention is to provide a process for making the above-described opening/closing device including the step of pressing and heating a pouring mouth 52 and a lid 54 from the side of a surface of a metallic film 56 in one action, in which the metallic film 56 can be thermally bonded to the pouring mouth 52 so that the bonded metallic film 56 can be easily peeled off.